Automatic pilot



Dec. 15, 1953 Filed Aug. 17, 1950 J. W. ANDERSON ET AL AUTOMATIC PILOT 4 Sheets-Sheet l AMPLIF'ER AILERW SERVO lZl HT 22 H5 9 l F W32 328 N120 :2532 329 L us J Ihwcmor JOHN W. ANDERSON RDBERT R. CHAPMAN MVVM Litiorneg Dec. 15, 1953 J. w. ANDERSON ETAL 2,662,705

AUTOMATIC PILOT Filed Aug. 17, 1950 4 Sheets-Sheet 2 3 IB 329 Bnmntor JOHN w. ANDERSON ROBERT R. CHAPMAN 17/5. /B B Gltorncg Dec. 15, 1953 J. w. ANDERSON ET AL 2,662,705

AUTOMATIC PILOT 4 Sheets-Sheet 4 Filed Aug. 17, 1950 EH5. wo zw N zo-m mm n mom :1 m mw N m M V m n T N AR T 1 A m m wR Y B mxmoihmz POJE -82 Q.

Patented Dec. 15, 1953 STATES PATENT OFFICE AUTOMATIC PILOT John W. Anderson, Edina, and Robert R. Chapman, Minneapolis, Minn., assignors to Minneapolis-Honeywell Regulator Company, Minneapolis', Minn., a corporation of Delaware Application August 17, 1950, Serial No. 179,982

13 Claims.

This invention relates to directional controlappar-atus for dirigible craft such as automatic pilots for aircraft. v

Such apparatus'is provided with stabilizing devices which maintain the attitude of the aircraft in preselected relation with respect to the axes of the craft. Such axes are termed the turn, roll, and .pitch axes. Devices which stabilize or control the craft with-respect tothe turn axis are referred toas directional control devices.

These devices maybe in the form of a free directional gyroscope, a compass responsive to the earths magnetic field, or a gyroscope slaved to a magnetic compass-termed a gyro-magnetic compass. I

it is an object of this invention to couple variou direction control devices alternatively with automatic controllapparatus having stabilizing means for another axis of the craft to increase the range of axis stabilization.

It is a further object of this invention to control such automatic control system from computing devices asalternative to control by said direction device'sl It is a further object'of this invention to permit manual selection between a device for stabilizing 'thecrait about'the turn axis and a computer device for also controlling the craft about the turr'i'axis.

It is a further object of this invention to pro- 'vide for novel'inanual control of the craft about the turn axisfroni a station remote from the station of'the pilot for the aircraft'w'hile a stabilizing device isrendered temporarily ineffective to control said c'raft'aboutthe turn axis during such manual control.

It is a further object of thi 'i'nvention'to gradually relinquish directional control from a stabilizing device and gradually introduce directional control from a computing device at'will.

Thes'e'and further objects of the invention will become apparent upon a consideration of the following detailed description taken in conjunction with the accompanying'drawing disclosing a prererred embodiment thereof.

In the drawing, Figures 1A, 1B jointly constitute a schematic-fo'r'm-of the novel apparatus, Figures 2 a'n'd'S' are fiow diagrams for two configurations, and Figure 4'15 a modification of Figures 1A and 1B.-

The form -ofthe invention schematically illustrated in the accompanying drawing, by way of example, is a system'for automatically controlling and stabilizing the attitude of an aircraft about the roll and turn axes of the craft. Control about the roll axis is provided by a conventional vertical gyroscope I14 while control about the turn axis may be effected either by a directional gyroscope GI, Figure 1A, or by magnetic compass associated control means 2I5, I91, I84, Figure 1B. When a directional gyroscope is utilized, it controls the system directly. On the other hand, when compass control means are utilized, motor driven means 86 controlled from the compass means are used to control the system through a normally energized magnetic clutch A remotely positioned manually operable means may be utilized to directly control the system at which time the directional gyroscope is placed in a caged condition or if the system is under compass control, the magnetic clutch I82 is deenergized and spring means 88, B9 serve to return to a normal position the motor driven means 85. With the compass control means being utilized therefor, the motor driven means 86 is 0perated to maintain the heading or attitude about the turn axis stabilized while additionally the manual means permits change in attitude of the craft about the turn axis.

The system may, alternatively to directional gyro or compass control, be controlled from a computer. When this selection of computer control is made, the control of the system by either directional gyroscope or the compass control mean is gradually diminished until it is made entirely ineffective and then the control of the system from the computer is gradually introduced from zero control to full control of the system.

For the purpose of more fully identifying the components of the system and their interrelationship a detailed description of the invention follows. Referring to the drawing which illustrate an automatic pilot system for an aircraft, the rudder (not shown) of the aircraft i operated by cables I9 (Figure 1A) extending from a cable drum II which in turn is driven by a rudder servomotor I2. The rudder servomotor is provided with a forward rotation clutch winding terminal I3; areverse rotation clutch winding terminal I4; and a brake winding terminal I5. The servomotor may be of the type disclosed in the patent to Hamby 2,466,702. The three rudder servomotor terminals are connected to the out contacts of a three-pole double throw rudder engage relay I6. 'The rudder servomotor I2 is reversibly controlled from a rudder amplifier 3I. The amplifier has alternating current power input terminal 21, 28 and alternating trol potentiometer 335.

current signal input terminals 29 and 36. The amplifier includes amplifier relay terminals 25 and 26 which are supplied from battery 24 upon closing of either amplifier relay. The relays are operated in discriminator manner in accordance with the phase relationship of the signal voltage across signal input terminals 29 and 3E! and the Voltage across power input terminal 21 and 28. Amplifier 3i may be of the type disclosed in the aforesaid patent to Hamby. Terminal 25 is connected to relay arm 23 which coacts with in contact Ii. Terminal 26 is connected to relay arm 22 which coacts with in contact I8. Relay arm 2| which coacts with in contact I9 is directly connected to battery 24.

Control signals across input terminals 29 and it of amplifier 3| are obtained from a balanceable control network E l. Network 34 comprises a servo balance-centering network 35; a vertical gyro roll axis potentiometer 43; a directional gyro yaw network 83; and a pilot operated turn con- Alternatively in place of the directional gyro network 6%] signals may be obtained from a compass control network 85.

Network 55 comprises a servo balance potentiometer 36 having a resistor 57 and a slider 38;

a transformer 49 having a primary winding ll and a secondary winding 52; and a centering potentiometer 43 having a resistor M and a slider 35. Resistors 37 and M are connected in parallel across the ends of secondary winding Q2. The slider 33 is operatively driven from-the rudder servomotor I2 through a suitable operating connection 46. Slider as may be manually positioned. A lead wire 41 extends from amplifier terminal 28 to slider 38.

Potentiometer 43 includes a slider 49 and a resistor 58 which is connected across a secondary winding of the main transformer. It is convenient to utilize a single primary winding for energizing a plurality of secondary windings and this arrangement has been adopted herein, therefore the same primary winding is indicated. Slider 36 is positioned in accordance with the deviations of the aircraft about its roll axis from a selected attitude by means to be described. A lead Wire 53 extends from slider 45 of potentiometer d3 to slider 49.

Network 56 includes a directional gyro potentiometer 5d having a slider 55 and a resistor 56 and a potentiometer 51 having a resistor 58 and an adjustable tap 59. Resistor 56 is connected across the ends of primary winding 5| in parallel with resistor 58 of potentiometer 43. Resistor 58 of potentiometer 5'! has one end connected to a center tap of secondary windin 5| and its opposite end connected to slider 55. Tap 59 is manually adjustable. Slider 55 is positioned with respect to resistor 56 in accordance with the change in heading of the aircraft with respect to a selected heading during stabilization. Slider 55 is positioned by directional gyroscope 6|.

The directional gyroscope 6| is of the conventional type having three degrees of angular freedom. The rotor of the gyroscope (not shown) is supported upon a horizontal axis within casing 62 and is provided with suitable driving means. The casing 62 is supported on an axis 68 in an outer gimbal ring 63 which axis is at right angles to the spin axis of the rotor. The outer gimbal ring 63 has trunnions 66 and 67 supported in bearings 65 and 64. The upper trunnion 66 positions slider 55 of potentiometer 54 with respect to resistor 56 upon change in heading of the aircraft during stabilization.

At times it is desirable to center and lock the slider 55 in its mid position on resistor 56 and for this purpose the gyroscope 6I is provided with a caging mechanism Hi. The caging mechanism it comprises a lug lI centrally disposed on the exterior of casing 62 in line with the spin axis of the rotor. Lug 'lI coacts with a hollow conical shaped member i3 mounted on a longitudinally slidable bar '32. Bar '52 is operated in one direction so that the conical shaped member 73 is engaged with the lug 7! to center and cage the gyro casing 62 and is moved in an opposite direction to be released therefrom. The bar 12 is operated by an uncaging winding It and a caging winding 75. Associated with the caging and uncaging windings l5 and M is a single pole double throw manually operable switch I6 having switch arm ll and spaced contacts 78 and i9; and a caging relay 86 of a single pole double throw type. The caging relay includes an arm BI which coacts with a caging contact 82 and an uncaging contact 33. The relay arm BI is biased to engage the uncaged contact 83 by biasing means 64.

Returning to the remaining portion of control network 3 the turn control potentiometer 385 includes a manually operable slider 386 and a resistor 3% which is connected across the ends of a secondary winding 538 of the main transformer. The secondary winding 388 has a grounded center tap which is common with the grounded terminal 38 of amplifier 3|.

An alternative to stabilization by directional gyro control from network 69 is provided by the variable impedance network 85 which also has a remote manually selective turn control. Network 35 comprises a compass output potentiometer 86, a bombardiers potentiometer 96, a secondary winding 93 of the main transformer, a compass maximum bank angle control potentiometer 9 3, and a fixed resistor 97. Potentiometer 86 includes a resistor 8i connected across the ends of secondary Winding 5'5 and a slider 88 biased to a central position by spring means 83. Potentiometer 9i includes a manually adjustable slider SI and a resistor 92 which is connected across the end of secondary winding 53 in parallel with resistor 82'. Secondary winding 53 has a center tap which is connected to a center tap of resistor 92. Potentiometer 2 comprises a manually adjustable tap 95 and a resistor 96 having one end connected to slider 83 and its other end connected in series with resistor 97 to the center tap of secondary winding 63.

Associated with the pilots turn control potentiometer s6 is a fader potentiometer I 82. P0- tentiometer I62 comprises a motor driven slider I63 and a resistor I8 3. The resistor is divided into a manual portion I95 and a computer portion I 66. The resistor includes end taps I67, I69 and a broad center tap I68. The motion of slider IE3 is limited by end stops III and III.

When compass control is to be utilized, the slider 55 of the directional gyro potentiometer is placed at its center position and turn signals from the compass potentiometer 85 are introduced between the slider 55 and slider 356 of the pilots turn control potentiometer.

For this purpose, a lead E66 extends from ad justable tap 6-5 of potentiometer 9d to end tap IIl'I of resistor Hit; A lead H2 extends from the fader potentiometer slider I63 now engaged with tap Nil to slider 55 of potentiometer 5 3. A lead wire I I3 extends from the center tap of secondary winding 93, an out contact I22 of a relay M4 to be described and the coacting relay arm 1,

control potentiometer 385. The center tap I08 of fader potentiometer resistor I04 is connected by lead wire I21, lead wire I28 to wire I25 connected to the center tap of winding 93 and it is thus apparent that as slider I03 of potentiometer I82 moves toward the center tap a decreased proportion of the signal from potentiometer B6 is suppliedto the network 34 for controlling amplifier 3 I.

When directional gyro control is to be applied to potentiometer 54, the compass potentiometer 86 will be unoperated and slider 88 will be in the center of its resistor 81. It will be now apparent that the rudder amplifier 3| is provided with a control circuit 34 which alternatively may include the, directional gyro operated potentiometer 54 or the comp-ass operated potentiometer 86.

The ailerons (not shown) are positioned from cables I38 extending from a cable drum I3I which is driven by an aileron servomotor I32. The aileron servomotor I32 is similar to the rudder servomotor I2 and includes a forward rotation clutch winding terminal I33, a reverse rotation clutch winding terminal I34, and a brake winding terminal I35. An aileron engage relay I38 which is of the four pole double throw type has three in contacts I31, I38, and I39 connected with the terminal of the servomotor I32. Associated with the relay contacts I31, I38, I39 are relay arms I43, I42, and MI respectively. An aileron amplifier I44 controls the direction of rotation of the servomotor I32 through the engage relay I38. The amplifier I44 includes alternating current input terminals I45, I46, alternating current signal terminals I41, I48, and amplifier relay terminals I49, I50. Relay arm MI is directly connected to battery 24 and terminals I49 and 558 of amplifier I44 are connected to battery 24 through operated amplifier relays as disclosed in the aforesaid patent to Hamby.

The control signal across terminals I41, I48 of aileron amplifier I44 is obtained from a network !54 which includes a servo balance-centering variable impedance network I55, a vertical gyro roll axis network I65, alternatively potentiometer 51 associated with the directional gyroscope network 89 or compass control network 85, and pilots turn control potentiometer 385.

The servo balance-centering network I55 comprises a rebalance potentiometer I56, a centering potentiometer I59, and a secondary winding I62 of the main transformer. Potentiometer I56 includes a slider I58 operatively driven from the aileron servomotor I32 through a suitable operating means I83 and a resistor I51 which is connected across the ends of secondary winding I62. Potentiometer I59 includes a manually adjustable slider I68 and a resistor IBI which is connected in parallel with resistor I51 across the secondary winding I62. A lead wire I64 extends from amplifier terminal I41 to slider I58.

The vertical gyro roll potentiometer I65 comprises a gyroscope potentiometer I66 and a secondary winding I88 of the main transformer. Potentiometer I88 includes a slider I81 and a resistor I58 which is connected across the ends of secondary winding I69. Slider I61 is positioned with respect to resistor I68 in accordance with the movements of the aircraft about the roll axis from a selective attitude. A lead wire I19 extends from slider I60 to slider I61. Network 68 and potentiometer 85 havebeen described with reference to the rudder amplifier input circuit. A lead wire I1I extends from a center tap of se ondary winding 1 9m adiustab e tan 5 o potenti mete 1- Th m ns whereby s ers I51 nd ,9 n n works I54 and 34 respectively are position d in accordance with the movement of the craft about the roll axis comprises a vertical gyroscope I14. The vertical gyroscope may be of any conventional type having a rotor (not shown) mounted for rotation about a vertical spin axis within a casing I15. The rotor easing I15 is journalled for rotation about a horizontal axis I19 in an outer gimbal ring I11. The outer gimbal ring I11 in turn is supported for rotation about a, horizontal axis I18 at right angles to axis I16 by pedestal bearings I19, I19. The gyroscope I14 is so arranged in the craft that upon movement of the craft about the roll axis from a selected attitude there will be a relative movement between gimbal I11 and pedestal bearings I19 about axis I18 which is communicated by suitable operating means I to sliders I61 and 49.

For operating the compass potentiometer 86, there is provided an operable driving connection I8I for slider 88 which through magnetic clutch I82 is coupled to the drive shaft or output shaft I83 of a control motor I84. The control motor I84 is of the capacitoreinductance type having a line winding I85, an amplifier winding I86, and a rotor I81. The line winding I85 is connected to the alternating current source through a phasing condenser I88. The amplifier winding I86 is connected to output terminals I89, I90 of an amplifier I9I.

The amplifier I9I is of the discriminator type and is provided with power input terminals I92, I93, and signal input terminals I94, I95. The amplifier-motor combination is well known and is such that current in the amplifier winding I86 will either lead or lag the current in line winding I85 depending upon the phase relationship between the signal voltage across terminals I94 and I95 with respect to the voltage across power input terminals I92, I93. Such phase relationship hence determines the direction in which motor I84 is operated.

The motor I84 drives a velocity generator I96 of known type having a, primary winding I91 connected to the source of alternating current and a secondary winding I98, inductively associated with primary winding I91 through rotor I99. The voltage induced in secondary winding I98 is dependent in phase and magnitude upon the direction and speed of, rotation of rotor I99. Across the secondary winding I98 there is connected in series a voltage dividing resistor 200 and a capacitor MI.

The input circuit connected to signal input terminals I94 and I95 of amplifier I9I is controlled by a double pole, double throw switch 202 and a manually operable single pole, double throw switch 208. Switch 2-02 includes switch arms 203 and 2-04. Switch arm 203 coacts with a computer contact 338 and a compass contact 205. Switch arm 2-04 coacts with a rebalancing network contact 206 and a ground contact 201. Switch 208 includes a switch arm 209 which coacts with a compass contact 2I0 and a compass bypass contact 2I I.

Compass controlled signals are provided by a control transformer 2I6. Control transformer 2I6 comprises a stator having three phase windings 2", H8, 2I9 anda rotor winding 220. The control transformer may be controlled through a coupling device, directly, by a, magnetic compass such as a flux valve compass or by a directional magnetic compass control maybe provided by a flux valve compass as disclosed in the patent to Stuart, Jr., 2,439,701. For example, the stator windings 28, 29 and 38 of the patent to Stuart conform to the windings 2I'I, 2I8, and 2I9 herein and the rotor winding 33 corresponds with the rotor winding 228 herein. When a slaved directional gyroscope as in Patent 2,484,862 to Streeter, Jr., is utilized a synchro transmitter controlled by the directional gyroscope has a three phase stator winding which is connected to the corresponding windings of the control transformer herein.

As has been inferred from a description of switch 282, it is also desirable to control the input circuit connected to terminals I94 and I95 of amplifier I9! from the computer 22I This computer is of known type which computes from various factors such as wind direction, airspeed, distance, etc., the course to be flown. It may be such as will provide an alternating output course control signal to output leads 222, 223. The system may function with various other types of course control devices one of which is disclosed in an application of Alderson et 8.1., Serial No. 49,442, filed September 15, 1948, where in Figure 7 conductors 495, 496 and 493, 494 are functionally substantially the same as conductors 222, 223 herein. Lead 222 is connected to computer contact 338 of switch 282 and lead 223 is connected to ground. The control circuit for the amplifier I9I during computer control in addition to the computer output includes a rebalance network 224. r

The rebalance network 224 comprises a rebalance potentiometer 225 having a resistor 226 and and a slider 221; a fixed resistor 228; a potentiometer 229 having a resistor 238 and a manually adjustable tap 23I; a fixed resistor 232; and a secondary winding 233 of a transformer. The resistor 226 is connected across the ends of secondary winding 233 and the slider 227 is operatively positioned by the output shaft I83 of the control motor I84 through a suitable operating connection 234. Resistor 228 has one end connected to the slider 22'! and its opposite end connected to one end of resistor 238 of potentiometer 229. The opposite end of resistor 238 is connected in series with resistor 232 to ground.

The secondary winding 233 has a grounded center tap.

During computer control of the amplifier I9I, the input circuit across terminals I94 and I95 of the amplifier comprises the computer 22I, the velocity generator energized voltage divider 288, and the rebalancing network 224.

During computer control of the amplifier I9I, there is provided a network 235 which transmits into the autopilot system signals proportional to the movements of motor I84 which have been controlled by the computer. The impedance network 235 comprises a computer output potentiometer 236 having a resistor 23'! and a slider 238; a secondary winding 239 of the transformer; a variable resistor 240; a fixed resistor MI; and a potentiometer 242 having a resistor 243 and a slider 244. Resistor 231 is connected across the ends of secondary winding 239. Resistor 243 of potentiometer 242 is connected across slider 233 and a center tap of secondary winding 239. One end of resistor MI is connected to an end of variable resistor 248 and their remaining ends are connected across the slider 238 and the center tap of secondary winding 239. Slider 238 is operatively driven from output shaft I83 of the control motor through the operating means 234, 243, and 245. The slider 244 of potentiometer 242 is connected by a lead 247 to end tap I89 of the fader potentiometer resistor. The center tap of secondary winding 239 is connected by leads 248, I21 to the center tap I88 of the fader potentiometer resistor I84.

It will thus be apparent that with the fader potentiometer slider I83 at the lowermost position which it may assume in the figure, the output voltage of network 235 which exists between tap 244 of potentiometer 242 and the center tap of secondary winding 239 forms part of impedance network 34 by connecting tap 244 through lead 241, end tap I89, slider I83, lead II2, to slider 55 of potentiometer 54 and connecting the center tap of secondary winding 239 through lead 248, lead I28, to slider 388 of the turn control potentiometer 385.

The fader potentiometer slider I83 is positioned from a fader motor 25! through an operating connection 256, a portion of its travel being represented in dotted lines. The fader motor may be a capacitor type induction motor having field windings 252, 253 across which is connected a phasing capacitor 254 and a rotor 255 inductively associated with the field windll'lgS.

The fader motor 25I is controlled by a manually operable bombardiers selector switch 251. Selector switch 257 includes a single pole double throw switch having a computer contact 258 and a manual contact 259 which are engaged by a switch arm 288. Switch arm 268 is operated from a rockable member 232 through an operating connection 23L The member 262 is pivoted at 293 and has biasing means 268 for returning it to the position shown. The member 2612 is provided with a. suitable cutout or slotted portion 2 64 which is engaged by a laterally offset portion 255 of a solenoid plunger 259. The plunger 239 is operated by a winding 268. The configuration of the slotted portion 234 is such that it together with the lateral extending portions 285 constitutes locking means for the member 262. The member 232 is thus solenoid controlled, the action being such that the member 282 cannot be moved from its manual position shown until winding 298 is energized. With winding 268 energized, it will be possible to move the member 252 in a clockwise direction whereby the connecting member 26: is cammed upwardly to move switch arm 258 to engage contact 258. When member 232 is thus operated, the operated plunger 289 engages the upper end of portion 284 which together serve as a holding mechanism for the member 262 to maintain the member in the operated position. If winding 268 be deenergized while plunger 239 is maintaining the member 262 in the operated position, return means 268 returns the member 282 to the manual position shown. If necessary it is also possible to manually override the holding action of yieldable plunger 269 to return the member to its manual position.

Operatively related with the slider I83 of the iader potentiometer I82 is a switch operating mechanism 218 for the compass-computer selector switch 282. The mechanism for example may comprise a forked member 2' pivoted intermediate its ends at point 272. The single end of the forked member is engaged by an over center spring 273 operating in compression. The forked ends of the member 2' form arms which are engaged by the member 274 of slider I83. The

arrangement is such that when the slider moves in one direction it operatively engages one arm of the fork member and when it moves in the opposite direction on return it engages the other arm of the fork member. Movements of the single end of the fork member are communicated by link 275, bell crank 216, and link 211 to arm 204 of switch 252. The arm 204 is o'peratively linked for joint operation with arm 203 through operating means 218.

Also associated with the operating mechanism 210 is a fader potentiometer slider operated gyro caging switch 280 of the single pole single throw type having a contact 28| and'an arm 232 chgageable therewith. The arm 232 is operated from the forked member 211 by operating means 213.

Also associated with the slider I03 of the fade'r potentiometer M2 is a magnetic clutch circuit control switch 233. This switch comprises two spring arms 254, 285 having contacts which are biased into engagement. An operating member 280 on slider i0 3 engages an extension of arm 284 to separate the contacts of switch 283 when slider 103 is in its uppermost position.

The relationship between the fader potentiometer resistor i8 3 and the switch operating means for switches 332, 280, and 233 is briefly set forth here. It is desired to operate the slider I03 so that it requires approximately 8 seconds for the slider to move from stop H0 to stop Ill. The center dead spot I03 is of such width as to correspond to one second of travel of the slider. The movements of slider I03 will effect operation of the switch 232 during the first quarter of second as the slider moves from the upper end of the dead spot is?! downwardly in the figure. The switch 200 is closed when the slider l03 enters the dead spot from the upper or manual end shown. The switch 233 is opened when the slider il-i enters the dead spot I01 from the lower toward the upper end as shown on the figure, and prior to the time that it engages the stop H0.

Switches 255i? and 283 are not used simultaneously or in a common system but are alternatively selected by a manually operable selector switch 281. Switch 237 is of the single pole double throw type having a switch arm 208 which may engage with one or the other of switch contacts 289, 293.

The arrangement for controlling the unlocking or" the bomhardier operable member 262 of selector 257 will now be considered. The slider 35 of potentiometer 90, in network 85, which comprises the bombardiers turn control signal means has its operating knob connected to its driven means 291. This driven means 29I serves as the operating means for a shaft 292. On this shaft 232 are notched discs 293 and 234. Operatively related with the notched disc 293 is a directional gyro caging-solenoid lock releasing switch 295. This switch comprises a switch arm I296 pivoted intermediate its ends with one end having a follower engaged with a notch 299 of disc 233 when the disc is in its normal position. The arm 2% has its free end coacting with a locking solenoid release contact 291 and a directional gyro caging contact 298. It will be apparent from the figure that as disc 293 rotates, a follower 3332 rides out of the notched portion 299 and engages the periphery of the disc 233 to disengage switch arm 256 from contact 291 and to engage it with contact 238.

The notched disc 29-; ccacts with a single pole single throw normally closed switch 30L Switch 301 is denoted the pilots transfer switch locking solenoid control switch and comprises an arm 302 pivotedintermediate its endsand having a follower 303 engaged in'a notch 304 of disc 294. The free end of switch arm 302 engages in normal position a contact 303. r

pilot operated transfer switch 306 serves to transfer control from the pilot to the remote station such as the bombardier station. Switch 306 is of the single pole double throw type having an operating arm 301 which may engage with a transfer relay contact 308 and an idle contact 309. Switch arm 30! may be held in its unoperated. position when the switch arm engages contact 303 by a solenoid operated plunger 310. Upon en'ergization of the winding 3 I I the plunger ismoved to release the switch arm 30! whereby it may be manually moved to engage contact 300.

A manually operable master switch 312 is provided. Switch 312 is of the single throw double make type having a bridge member 3l3 which engages simultaneously contacts 3 l4 and 3 IS. The switch is normally in open position and when closed serves to couple a battery 316 to a main D. C. bus bar 3".

Operation The operation of the control system will be considered with a configuration wherein the di= rectional control is provided in one case by a directional gyroscope or by a computer and in a second case where the directional controller is provided by a synchro transformer controlled by a magnetic compass or slaved gyroscope with alternative control being provided by a computer. The directional gyroscope-computer configuration will be considered first.

During control from a directional gyroscope, switch arm 11 of manual control switch 76 engages contact 18, switch arm 203 of manually operable switch 208 engages contact 2, and switch arm 288 of manually operable switch 28'! engages contaot290.

With the craft airborne and with the control surfaces being manually operated, the directional gyroscope 6| is in a caged condition. This cag i'ng is effected by a circuit extending from battery 24, arm 2| of rudder engage relay 16, out contact 20, lead wire 3|0, caging relay 80, to ground, and to battery ground return. With relay 30 operated, 'a circuit is now completed from battery 24, lead 3l9, ca'ging relay arin 8|, in contact 32, caging winding 15 of caging mechanism 10, to ground, to battery ground. The directional gyroscope 6| is thus held in its center position during manual flight. With the craft in level position and headed in the desired direction, the pilot may operate switch 3| 2 completing a circuit from battery 316, switch 3I2, D. C. bus 3, a parallel path comprising rudder engage relay l 6, to ground, and aileron engage relay 136 to ground, and return to battery. The aileron and rudder servomotors are now engaged with their respective control surfaces. The directional gyroscope is now uncaged since the circuit to caging relay is broken between switch arm 2! and out-contact 20 of the rudder engage relay permitting spring 34 to move arm 8| into abutment with contact 83 to energize uncage winding 14.

With the autopilot so engaged, any deviation of the craft from the desired heading will be corrected by the directional gyroscope BI, and its potentiometer 5 4 which supplies control signals for the rudder and aileron and any change in attitude of the craft about the roll axis will be corrected by vertical gyro (14 through the potentiometers I66 and 48 in networks 154 and 34 11 which supply bank correction and rudder compensation signals.

When the pilot desires to change the heading of the aircraft, he operates the pilots turn control potentiometer 305 and moves simultaneously through the operating connection I 23 the arm I24 of switch I23 into engagement with contact I21 or 120. The caging relay is thereby enchanged heading the desired amount, the turn control potentiometer is returned to its normal position at which time the arm I 24 disengages its engaged contact and the caging relay moves to its unoperated position with arm 0! engaging contact 83 completing a circuit from battery 23, lead 3I9, switch arm 05, out contact 33, switch arm 11, contact 13, to the uncaged winding 14 of caging mechanism 10, to ground, and to the ground of battery 24.

The pilot may transfer control of the automatic control system to the bombardier who is at a station remote from the pilot's position. For this purpose the pilot operates the transfer switch 306 so that arm 301 engages contact 303. Before the pilot may operate the switch arm 301 the bombardiers turn control potentiometer 90 must be in normal position so that the follower 303 which coacts with the disc 204 engages the notch 330 of said disc. This setting of notched disc 234 completes a circuit from battery 23, arm MI of the aileron engage relay I36, in contact I39, lead 322, arm H0 of relay II i, out contact I20, lead 323, switch arm 302, contact 305, lead 320, winding 3 of the locking relay, to ground, and to the ground of battery 24.

With the transfer switch arm 301 to the left a circuit is completed from battery 3IE, switch 3I2, contacts 308, switcharm 301, lead 325, to relay II4, to ground, and to the ground of battery 3 I 6.

With the operation of transfer relay H3, the locking means 259 of the bombardier selector 251 is moved to releasing position and this is effected by a circuit extending from battery 3H3, switch 3I2, D. C. bus 3I1, lead 326, relay arm H5, in contact i8, lead 321, switch arm 2%, contact 291, lead 328, solenoid operating coil 208, to ground, and to the return of battery 3 I 5.

With the transfer relay II energized, which thereby maintains a holding circuit for coil 3! l, the bombardier may determine whether he shall provide bombardiers manual turn control or control from the computer. Reference is now made to Figure 2 which is a simplified flow diagram of the arrangement using a directional gyroscope in combination with a computer. With the memher 252 in its position shown in Figure 1B, the pilot may operate the bombardiers turn control potentiometer 30 to manually make changes in the heading of the craft. The output of the bombardiers turn control potentiometer 00 is applied across portion I05 of the fader potentiometer resistor which with the fader potentiometer slider 03 forms a voltage divider for the output of the bombardiers turn control potentiometer. This is obtained by connecting lead I00 representing one side of the output of potentiometer 00 to one end of resistor I05 and connecting the other end of resistor portion I05 by means of lead I21, lead I28, lead I25, relay arm H1, in contact iii, to lead 329, connected to $11 1? ,9! of potentiometer 90.

If the bombardier desires to introduce computer control he may move the control memher 262 clockwise to engage switch arm 200 with contact 258. The fader motor 25I for driving slider I03 is now energized, a circuit being completed from an alternating current source, switch arm 280, operated contact 258, lead 330, through fader motor windings 253 and 252, to ground, and to the ground of the supply. The fader motor slider now begins to move in the downward direction in Figure 1B or counterclockwise in Figure 2. As slider I03 enters center deadspot I08, switch 280 is closed thus completing a circuit from battery 3I0, lead 3I1, arm 208, contact 290, lead 333, switch 280, leads 334, 335, 332 for energizing the caging relay and thus caging the directional gyroscope.

As the slider I03 of the fader potentiometer enters the center dead spot I08 as stated, switch arm 203 is operated also and is brought into engagement with computer contact 338 while the switch arm 282 of caging switch 280 is operated as mentioned to engage contact 28L The movement of slider I03 of the fader potentiometer to its mid position has been indicated in Figure 2 as resulting in the directional gyroscope GI being made ineffective with respect to the control networks 34 and I54.

With the operation of switch 202 at the time arm 203 engages contact 338 as stated, the input circuit across terminals I04 and I of amplifier Isl extends from terminal I90, lead 2I2, resistor 2I3, switch arm 203, contact 330, computer lead 222, ground lead 223, grounded resistor 232, voltage divider 229, lead 340, contact 208, switch arm 204, lead 3, voltage divider resistor 230, lead 342, and amplifier terminal I35. A signal from computer 22I initiates operation of the amplifier I05 which causes the operation of the control motor I24. The control motor through its output shaft I83 and driving connection 233 operates slider 221 of the rebalance potentiometer 225 and simultaneously through the operating connections 240, 265, drives the slider 238 of the computer output potentiometer 236. The motor 530 drives the slider 221 until the net output of network 220 which includes potentiometer 225 corresponds with the computer input, the velocity generator I 06 meanwhile provides an antihunt control for motor I 84.

As the fader motor slider I03 moves toward its lower end in Figure 1B from center tap i08, it is apparent that it introduces into the autopilot control networks signals from the network 235 which includes computer output potentiometer 236 in a gradually increasing manner since the portion I 05 of the fader potentiometer resistor I04 along with slider I03 constitutes a voltage divider across the network 235. The control signal as determined from the computer 22! is thus gradually applied from network 235 to networks 34, I54 until the full value of the full output of network 235 is applied to the networks 34 and I50.

When the bombardier desires to return to his manual control, the control member 232 is moved counterclockwise in Figure 13 to its position illustrated, and the fader motor 25I is energized in the opposite direction to move the slider I03 toward its upper position as shown in Figure 1B or clockwise as shown in Figure 2. The switches 202, 203, and 280 are operated as the slider goes through the center dead spot I08 of potentiometer resistor I 04. With the switch arm 203 en-,

gaged with contact 205, the computer 22I is no 13 longer connected to amplifier I9I. Any residual signal in computer output network 235- due to displacement of slider 238 will be of no effect once the slider I03 oi the potentiometer reaches the dead spot I08 in its progress from the lower to the upper end as shown in Figure 113.

If computer control is reintroduced with a residual signal in network 235, the width of the dead spot I08 at the center of resistor I04 is of sufficient length to permit the computer 22I to effect positioning of the slider 238 in proportion to the computer input before the slider I03 leaves the center dead spot and moves toward the lower end of the fader potentiometer resistor as shown in Figure 1B. The control motor I84 operates slider 22! of the rebalance potentiometer 225 at a speed such that it requires but /3 of a: second for the slider to be operated from one extreme position to the other so that ample time is provided for eifecting the positioning of the computer output potentiometer slider 238 in accordance with the computer input value.

We may now consider the second configuration wherein directional control is supervised by the control transformer operated by a flux valve compass instead of the directional gyroscope which compass may be thus placed in combination with the computer 22I. The flow diagram for this arrangement is illustrated in Figure 3. As a preliminary, switch arm 11 of switch 16 is manually engaged with contact I9, switch arm 208 of switch 208 is engaged with contact 2I0, and switch arm 288 is placed in engagement with contact 289. With the fader potentiometer slider I03 in its upward position in Figure 1B or in its right position as shown in Figure 3, the circuit extending from battery 24, lead 3I9, caging relay arm 8I, contact 83, switch arm 11, contact 73, lead 350, magnetic clutch I82, to ground and to return of battery 24, energizes the magnetic clutch to couple the output shaft I83 of the control motor I84 to slider 88 of the compass output potentiometer 88.

Any deviation of the craft from the desired heading results in a signal being applied from the magnetic compass transmitter to the rotor 220 of the control transformer 2IE. One end of control transformer rotor 220 is coupled by lead 2I5, contact 2I0, switch arm 208, lead 2I4, contact 205, switch arm 203, resistor 2I3, lead 2I2, to amplifier terminal I84. Amplifier terminal I95 is connected by lead 342. velocity generator voltage divider 200, lead 34I, switch arm 204, contact 201, to ground, and to the opposite or grounded side of rotor 228. The amplifier ISI operates under the signal in rotor 22 and effects rotation of control motor N34 to position the rotor 220 to a null position the operation being effected by output shaft I 83, operating means 234, 248, gear train 249, and operating connection 250. At the same time, the control motor drives the slider 88 of the compass output potentiometer 86.

Signals from potentiometer 83 are applied across iader resistor portion I which with slider I03 forms a potential divider. With the slider I03 at the manual or upper end of the potentiometer resistor as shown in Figure 1B the full voltage from potentiometer 86 modified by tap 95 is applied between lead II2 leading to control networks 34 and IE4 and lead I26 connected to ground through the pilot turn control potentiometer 85. As the craft moves toward the magnetic heading being maintained, an opposite signal is induced in rotor 220 of control transformer ZIB energizing amplifier I9I and causing the reverse movement of control motor I84. Slider 88 of potentiometer 88 as well as the control transformer rotor 220 are moved back to their normal position with respect to their resistors and three phase windings respectively.

'If th bombardier wishes to execute a manual control turn, he operates the bombardier potentiometer 80. This operation also rotates notched disc 293 so that switch arm 296 engages contact 298 thereby completing a circuit from bus 3II, lead 326, switch arm H5, contact II8, lead 321, switch arm 296, contact 298, lead 332, to the caging relay 80. Relay 80 operates and moves relay arm -8I out of engagement with contact 83 thereby breaking the circuit for the magnetic clutch I82 between relay arm BI and contact 83. With the magnetic clutch deenergized, the

driv between output shaft I83 and slider 081s disengaged and spring means 83 restore the slider 88 to its normal position. Were the 'fader slider I03 in its manual position as shown in Figure '3, the full signal from the bombardiers potentiometer is applied between lead I28 and lead '2 to efiect operation of the autopilot amplifiers and the consequent operation of the control surfaces to change the heading of the aircraft.

Such manual changes in heading of aircraft which result in a signal being set up in control transformer rotor 220 cause it to operate the amplifier IQI and the control motor I84 which operates the rotor 220 to maintain it in a null position during bombardiers changes in heading.

If the bombardier desires to obtain computer control, the selector member 282 is moved toward the upward position or clockwise in Figure 1B thereby energizing the fader motor 25I. The motor 25I drives the slider I03 toward the downward position from end tap I01 in Figur 1B or leftward in Figure 3.

As soon as slider I03 leaves the manual end, switch 283 is permitted to close completing a. circuit from D. C. bus 3H, switch arm 288, contact 288, lead 360, switch 283, lead 36I, lead 335, lead 332, to the caging relay 80. Upon operation of caging relay 80 th circuit for the magnetic clutch I82 is broken between relay arm 8| and contact 83. The spring means 88 of potentiometer 86 center the slider 80 upon opening of the magnetic clutch I82. As the slider I03 passes through the center dead spot I08 of resistor I04, it operates the switch 202 to engage switch arms 203 and 284 with contacts 338 and 206.

The control circuit of amplifier I9I now includes the computer 22I, the output of velocity generator I06, and the rebalancing network 224. The computer 22I will control the amplifier I3I and the control motor I84 to effect operation of the slider 22'! of the rebalance potentiometer 228 in proportion to the input signal from the computer. This operation of slider 22! is accom panied by displacement of slider 238 in the computer output network 235. The network 235 will therefore control the autopilot networks 34 and I54 and the autopilot amplifiers 3I and I44. The efiect of network 235 is gradually introduced as the fader potentiometer slider I 03 moves from the center dead spot I03 toward the lower end tap I03 in Figure 1B.

As the aircraft approaches computer called for heading, the signal from the computer 22I decreases and the signal from the rebalance network. 224 predominates, effecting reverse rotation of the control motor I84 so that when the computer output is zero the slider 22! of the rebalance network 224 and the slider 238 of the 15 compass output network 235 are again at normal positions. i

The control motor I84 has also driven through the gear train'249 having a 6 to 1 speed reduction the rotor 220 of the control transformer 2I6. This forward and reverse rotation of the control motor I84 has vnot resulted ultimately in any changein position of the rotor 220 with respect to the three phase windings 2I1, M0, and 2I0. It is apparent therefore that this change in heading as determined by the computer will leave a residual signal in rotor 220 of control transformer 2 I6. If it be: desiredto return the fader slider I03 to the manual end, the bombardier operates the control member 262 to its downward position shown in Figure 1B. As slider I03 passes upwardly through the center dead spot I it again moves the switch 202 causing switch arms 203 and 204 to engage contacts 205 and 201. With the aforementioned residual signal in rotor 220, it would appear upon operation of switch 202 that the amplifier I0! would effect operation of slider 88 through the control motor I 84. However, the magnetic clutch I82 remains deenergized until slider I03 is at the extreme manual end of the resistor I04 at which time the switch 283 is opened.

The arrangement is such that the rotor 220 of the control transformer will be placed in a null position before the switch 283 is opened by slider I03 as willbe apparent from the following discussion. It was stated that approximately 8 seconds is required for fader slider I03 to move from stop to stop on the fader potentiometer resistor. The speed of the output shaft I83 is about 60 R. P. M. and the speed of the output shaft 250 from gear train 249 is about 10 R. P. M.

their This corresponds with one revolution per secend and /6 of a revolution per second respectively for these shafts. With the center tap I08 of resistor I04 equal to a one second interval and an eight second period for the entire travel of slider I03, it is evident that there are '7 half seconds remaining between the time slider I03 leaves the dead spot I00 and until it reaches stop H0 in Figure 13. While the rotor 220 of transformer 2 It can be driven at a speed of one sixth revolution per second and there is available three and one half seconds between the time the signal from rotor 220 is applied to amplifier HH and the time of closing of the clutch I 82 and since the greatest angular deviation rotor 22 can have with respect to its stator windings is 180 degrees or 3 seconds time of travel, it is apparent that rotor 220 will be placed in a null position with respect to its stator before the slider I03 opens the switch 283 at the end of its travel. Thus any residual signal remaining in control transformer 220 due to change in heading of the aircraft under computer control will merely result in operation of motor I 84 to place the rotor in a null condition before compass control is applied to the compass output potentiometer 86.

Figure 4 illustrates in schematic form a modification of a portion of the arrangement shown in Figures 1A and 1B. The substitution or modification in Figure 4 consists primarily in substituting relay operated switch arms for the motor operated switch arms 203, 204, and 232 of Figure 1B and additionally substituting a further pair of relay contacts associated with network 85 to replace the upper end I of the fader potentiometer I02. This results that upon a 'bombardiers selected change from compass 16 control to computer out initially the compass signal as the iader potentiometer slider I00 moves from the manual end toward the center tap H00 in Figure 1B the control of the craft by the compass is immediately suspended and computer control of the craft begins to fade in.

A further change in the circuit is the provision of a further relay which is energized upon the operation of a switch, either manually or by automatic means, to disassociate the control of the autopilot from computer and to introduce the compass control of the automatic pilot.

Referring to Figure 4, the elements of the overall arrangement which have their corresponding parts in the arrangement of Figures 1A and 1B are identified by the same reference characters. Thus, there is the selector switch 307 located at the pilots position which when moved to the operated position will energize the relay H4. structurally, the pilots selector switch 37 and the bombardiers switch 200 are similar to the bombardiers switch 202 of Figure 1B. Thus, both the switch 301 and the switch 250, if in the operated position, drop into and lock in the unoperated position when the individual locking solenoid for each switch is not energized. When the respective solenoid for each switch is energized, the switch may be moved from unoperative to operative position and is automatically held in this operated position with permissible manual override. The individual solenoids for switches 007 and 260 correspond with the solenoid 268, 269 of Figure 13.

It will be recalled that the bombardiers switch 260 is moved from its manual contact 250 to its automatic contact 259 when it is desired to introduce computer control of the automatic pilot. In the arrangement of Figures 1A and 1B the operation of switch 200 caused operation or" the fader motor which in turn (in the arrangement of Figures 1A, 1B) operated during its movement the switch arms 203, 204, and 202. It has been found desirable to omit the motor operation of the switch arms and to operate manually a second switch arm 40! simultaneously with the switch arm 200 through an operating connection 400. The operation of arm 40! en a es a contact 402 to energize an operating coil 404 of a K-3 relay which replaces the fader motor as a switch operator.

The K-3 relay has a switch arm 405 which coacts with an in and an out contact; a switch arm 408 which coacts with an in and an out contact; and a switch arm 407 which coacts with an in and an out contact; and a switch arm 008 which coacts with only an in contact. Relay switch arm 405 replaces motor operated switch arm 203 of Figure 1B whereby to change from compass or directional gyro heading control to computer heading control. The relay arm 305 replaces the motor operated switch arm 204 whereby the rebalance potentiometer 225 operated by control motor E84 may be included or omitted from the input circuit of amplifier MI. The relay operated switch 40% corresponds to the motor operated switch arm 202 and thus serves to deenergize the magnetic clutch 02 to thereby disassociate the compass potentiometer slider 88 from the drive shaft its from control motor I84.

Switch arm 40'! of the Iii-3 relay functionwise replaces the upper end I05 of the fader potentiometer I02 and the conductors i223 and 329 associated therewith. This switch arm 00? and control instead of fading 17 its associated contacts serve to connect the computer output potentiometer 236 to the autopilot input lead H2 and to simultaneously disconnect from the autopilot lead I I2 the network 25 which includes the compass output potentiometer 86 and the bombardiers potentiometer 90.

The relay has been shown in its entirety with its operating coil #84 but the switch arms and their coacting contacts have been illustrated again in the circuit arrangement to bring out more clearly the function of each switch arm and its related contacts.

A K-4 relay is provided with a single switch arm 4! l which coacts with an out contact. The solenoid of the K-4 relay is energized through a single pole single throw switch 4H} which as stated may be manually or automatically operated for example from the bomb bay doors or similar apparatus on the aircraft.

The operation of the arrangement of Figure 4 will now be considered when the compass directional stabilization of the craft is utilized at which time the switch arm 238 is engaged with the right contact 2% and the switch arm 289 is engaged with the left contact 210 of the compass synchro so that the output of the compass synchro is applied to the control motor amplifier [91. We may assume that the aileron engage relay 136 and the rudder engage relay it, Figure 1A, have been energized and in the aileron engage relay, the relay arm l4! engages its in contact [39.

Preparatory to the pilots operating the switch arm 391', which as stated is of the solenoid controlled type, the bombardiers potentiometer 90 must have its slider 9| in center position so that switch arm 3B2 operated with the slider engages contact 335 to thus close a circuit to the solenoid coil 3!! through an out contact I of relay 154. With solenoid 3H as thus energized, the switch 35? is released from its locking soleinoid and the pilot may engage switch arm 38! with con tact 398. This closes the circuit through the operating coil of relay i It which operates the three relay arms H5, H6, and H1. Switch arm H5 maintains a holding circuit for relay coil 3H; switch arm H5 supplies direct current to switch arm 2% operated by the bombardier; switch arm H! engages contact [21 to permit bombardiers potentiometer 9!} to control the course of the aircraft.

At this time the output of the synohro 220 controls the heading of the aircraft and changes in heading may be provided by the bombardier operated potentiometer 60.

In order to introduce computer control, the

bombardier will move the switch arm 25!}, which is of the solenoid controlled type, from contact 258 to contact 258. Before switch arm 26% may be operated the slider 9| of the bombardiers potentiometer 98 must again be in center position at which time the switch arm 298 operated along with the slider 9| is in engagement with contact 291 to complete a circuit through coil 26% to energize the same and thus to unlock the switch arm 250. With the manual movement of switch arm 2% into engagement with contact 259, the arm 33! is also manually operated into engagement with contact 402 to energize the K-3 relay. 1

The switch arm ill! of the K-3 relay engages its in contact to connect in the computer output potentiometer, the switch arm 4B5 engages the computer contact 338 to connect the come put-er to the amplifier lei, the switch arm 485 engages its in contact to include rebalance potentiometer '225 in the input circuit of amplifier I91, and switch arm 468 engages its in contact to energize the relay winding of relay 8! which opens the circuit to the magnetic clutch I82 and permit the slider of the compass output potentiometer 86 to be spring centered. As the slider I03 of the fader potentiometer moves toward the lower end of resistor portion H38, the control of the autopilot from the computer is gradually introduced until full control is exercised when the slider IDS is at the lower end of resistor portion I08.

lhe computer may be of such type as to direct automatically the craft over a selected target.

fter the craft passes over such target, the computer would endeavor to control the craft so that its course would again bring it over the target. In some cases it may be desirable to prevent this control, consequently, the switch 410 for controlling the K-4 relay may be closed during the operation of dropping the bombs on the target.

With the K-4 relay energized, its switch arm 4H breaks the circuit to coil 26% associated with the bombardier selector switch arm 26 The switch arm 260 at this time drops back to unoperated position and is locked therein. In this position it engages contact 253 and switch arm 4M moves off contact 402. Engagement of switch arm etc with contact 258 causes a reverse movement of the fader motor 25!. The movement of arm 48! from contact 482 opens the circuit of the 31-3 relay. The deenergization of the K-3 relay again introduces compass control of the craft for autoinatically stabilizing its heading with manual changes in such heading being provided by the bombardiers potentiometer 923.

The primary purpose in providing the modification shown in Figure 4 is to omit the delay in transferring from compass to computer control which is inherent in the arrangement of Figures 1A and 1B which requires the fader potentiometer slider I03 to move to the dead spot Hi8 on the potentiometer before the computer control is introduced. Additionally the automatic return of course stabilization from computer to compass is automatically provided by the K- l relay.

It is now apparent that we have provided a novel control system wherein a plurality of directional stabilizing devices may selectively be utilized to control automatic means for operating the control surfaces of the craft. It is further evident that there has been provided an automatic control system which selectively permits the alternative control of the craft operation from a plurality of direction control devices and such alternative selection is obtained without abrupt operation of the control surfaces.

While many widely different embodiments of the invention could be made without departing from the essence thereof, it is to be understood that this disclosure is merely illustrative of one embodiment of the invention. What is claimed as new is:

1. Apparatus for operating the control surfaces of a dirigible craft comprising: a voltage responsive servo mechanism for controlling operation of said control surfaces; heading stabilizing means for producing a voltage in response to change in heading of said craft; computer means for producing a voltage in proportion to a desired heading; follow-up means for producing a servo mechanism operation limiting voltage; means for selectively applying said voltages to said mechanism including means for shifting conae'eavo's F. ...19 trol of said voltage responsive servo mechanism from said heading stabilizing means to said computer; and delay means for controlling sa d servo mechanism from said servo operation limiting voltage and said computer voltage an interval prior to control of said surfaces from said mechanism to prevent abrupt change in heading of said craft.

2. Apparatus for operating power means adapted to adjust control surfaces of a dirigible craft comprising: a voltage responsive servo mechanism for controlling operation of said control surfaces power means; stabilizing means for producing a voltage in response to change in heading of said craft; computer means for producing a voltage in proporton to a desired heading; follow-up means for producing a servo mechanism operation limitingvoltage, means for selectively applying said voltages to said mechanism including means for shifting control of said voltage respons ve servo mechanism from said stabilizing means to said computer, and means to introduce gradually the controlled proportional operation of said control surfaces power means by said servo mechanism.

3. Control apparatus for an aircraft having control surfaces for controlling the heading thereof comprising: servo means for operating said surfaces; signal respons-ve means for controlling said servo means; first station means for providing a signal for said signal responsive means; a second station means for providing a signal for said signal responsive means; transfer means at said first station for enabling said second station means to eifect control of said signal responsive means; and means for preventing operation of said transfer means while said second station means is providing a signal.

4. Control apparatus for an aircraft having control surfaces for controlling the heading thereof comprising: servo means for operating said surfaces; signal responsive means; connec tions therefrom to said servo means for operating said servo means; heading stabilizing means for providing a signal; a first stat on means for providing a signal; connections from the stabilizing means and first station means to said signal responsive means; a second station means for providing a signal; transfer means at said first stat on for enabling said second station means to effect control of said signal responsive means; and means for preventing operation of said transfer means while said second station means is providing a signal to prevent sudden operation of said servo means; and means for rendering said stabiliz ng means ineffective to provide a signal upon operation of either said first or second station signal providing means, whereby said heading stabilizing means does not oppose changes in heading from the first or second station.

5. Control apparatus for operating the control surface of a dirigible craft comprising: servo means adapted to move said surfaces; signal responsive means for controlling said servo means; a manually operated signal producing device; a device for automatically producing a signal in accordance with a desired heading; motor operated means for shifting control of said signal responsive means from one of said signal devices to said other signal device, said means gradually diminishing the effect of one signal device and subsequently increasing the effect of the other signal device; and means for preventing initial control of said signal responsive means from said manually operated device until said device has been placed in no signal producing position.

7. Control apparatus for operating the control surfaces of an aircraft comprising: servo means adapted to move said control surfaces; signal voltage responsive means for controlling said servo means; a control transformer having a rotor for producing a voltage in accordance with change in craft heading; computer means for producing a heading control voltage; means for alternatively selectively connecting said computer voltage producing means and said rotor with said signal responsive means; and motor means for placing said rotor in a no signal producing position prior to control of said servo means by said signal voltage responsive means.

8. Control apparatus for operating the control surfaces of an aircraft comprising: servo means adapted to move said control surfaces; means for controlling said servo means; signal voltage responsive means; a control transformer having a rotor for producing a voltage in accordance with change in craft heading; computer means for producing a heading control voltage; means for connecting said computer voltage producing means or said rotor with said signal responsive means; a first and second independent means for operating said servo control means from said signal responsive means while it is under computer or rotor voltage control respectively; and means for maintaining the second means for operating said servo control means in unoperated condition during connection of said computer signal producing means with said signal voltage responsive means.

9. Control apparatus for an aircraft comprising: voltage responsive servo means for controlling the attitude of said craft; stabilizing means for producing a voltage signal; computer means for producing an attitude control voltage; means for connecting either of said Voltage producing means with said voltage responsive means; further means for rendering said stabilizing means ineffective to produce a voltage; and transfer means for progressively decreasing the effect of said computer voltage on said Voltage responsive means and for rendering said further means ineffective when said computer voltage has no effect on said voltage responsive means.

10. Apparatus for controlling the attitude of an aircraft about an axis thereof alternatively in response to two control devices comp-rising: means including a device responsive to change in attitude of said craft; operable means for controlling the attitude of said craft; a computer device for predetermining the attitude of said craft; and transfer means coupled to said computer device and said attitude responsive device and said operable means and progressively decreasing the effect of one device and thereafter increasing the effect of the other device on said operable means whereby the attitude of the craft is substantially unchanged between transfer of control effects of said devices on said operable means.

11. Apparatus for controlling the attitude of an aircraft about an axis thereof alternatively in response to two control devices comprising: means including a device responsive to change in attitude of said craft; operable means for controlling the attitude of said craft; a computer device for predeterminingthe attitude of said craft; and transfer means coupled to said computer device and said attitude responsive device and said operable means and progressively decreasing the efiect of one device and thereafter increasing the effect of the other device on said operable means whereby the attitude of the craft i substantially unchanged between transfer of control effects of said devices on said operable means; and manually actuable means for controlling said operable means and eifective on operation to render said attitude responsive means ineffective on said op- L erable means.

12. Apparatus for controlling the attitude of an aircraft about its turn axis selectively in re sponse to a plurality of signal devices, said apparatus comprising: means including a signal device responsive to change in heading of said craft; a computer signal device for predetermining the heading of said craft; a manually operable signal device for selecting the heading of said craft; operable means for controlling the attitude of said craft; and transfer means coupled to said computer signal device on the one hand and said attitude responsive device and said manually operable signal device on the other hand and progressively decreasing the efiect of the one signal device on the one hand and thereafter increasing the effect of the other two signal devices on the other hand on said operable means whereby the attitude of the craft is substantially unchanged between transfer of control eifects of said signal devices on said operable means.

13. Apparatus for controlling the attitude of an aircraft about the turn axis thereof alternatively in response to two control devices comprising: a first voltage producing device responsive to change in heading of said craft; a computer device for producing a signal voltage in accordance with a predetermined heading of said craft; potential responsive mean for controlling the attitude of said craft about the turn aXis; and transfer means coupled to said computer device, said attitude responsive device, and said operable means and progressively decreasing the effect of one device and thereafter increasing the effect of the other device on said potential responsive means whereby the attitude of the craft about the turn axis is substantially unchanged between transfer of control effects of said voltage producing devices on said voltage responsive means; and manually operable means for producing a voltage signal in accordance with desired changes in heading and connected in parallel with said attitude responsive device to said transfer means; and means for rendering said attitude responsive signal generator ineffective during operation of said manually operable voltage producing device.

JOHN W. ANDERSON. ROBERT R. CHAPMAN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,410,468 Van Auken et al. Nov. 5, 194 2,429,642 Newton Oct. 28, 1947 2,450,907 Newton et a1 Oct. 12, 1948 2,466,702 Hamby Apr. 12, 1949 2,515,349 Kutzler et al. July 18, 1950 

